Acoustically improved blower package

ABSTRACT

A housing is formed of a block of sound absorbing material of sufficient density to retain its form. A scroll-shaped chamber is formed in the block of sound absorbing material for locating a blower. A passage is formed in the housing which extends from an outer surface thereof to the scroll chamber. The passage forms a built-in muffler in the block of material. A diffuser is formed in the block of material which leads from the scroll chamber to an outer surface of the housing. A thin material coating is applied to the inner surfaces of the sound absorbing material block to prevent the material from eroding and to present a low friction surface to air passing thereover. A stiff outer shell surrounds the housing and has a good sound reflective characteristic. The shell has openings therein corresponding to the inlet opening of the muffler passage and the outlet opening of the diffuser.

8 United States Patent Antonetti et al.

[4 1 Sept. 5, 1972 [54] ACOUSTICALLY IMPROVED BLOWER PACKAGE [73] Assignee: International Business Machines Corporation, Armonk,N.Y.

[58] Field of Search.....18l/33 R, 33 K, 35 C, 61-63, 181/42, 50, 58, 33 G; 415/119; 417/312 1,018,084 1/ 1966 Great Britain 1 81/50 Primary ExaminerRobert S. Ward, Jr.

Attorney-Harold H. Sweeney, Jr. et al.

[5 7] ABSTRACT A housing is formed of a block of sound absorbing material of sufficient density to retain its form. A scroll-shaped chamber is formedin the block of sound absorbing material for locating a blower. A passage is formed in the housing which extends from an outer surface thereof to the scroll chamber. The passage forms a built-in muffler in the block of material. A diffuser is formed in the block of material which leads from the scroll chamber to an outer surface of the housing. A thin material coating is applied to the inner surfaces of the sound absorbing material block to prevent the material from eroding and to present a [56] References Cited low friction surface to air passing thereover. A stiff outer shell surrounds the housing and has a good UNITED STATES PATENTS sound reflective characteristic. The shell has openings 2,705,541 4/1955 Finch ..l81/50 therein corresponding to the inle opening of the muf- 3,174,682 3/1965 Wilfert et a1 ..415/1 19 fler passage and the outlet opening of the diffuser.

48 ,443 121 69 Eahart ..415 119 5 I 9 r 11 Claims, 5 Drawing Figures FOREIGN PATENTS OR APPLICATIONS 746,702 3/1956 Great Britain ..l8l/33 K 24 22 54 L l I I I l I T 152:: -52 5- 1') 54 5 1 L 4 4 1;? t 3 I I I I! I ,4 L%J T 17 10 l I L. L-, J26 "-"r- 44L 1\ 10/ 52 g \L iaz 54 25 LM M 25 541i PA TENTED 5 I972 SHEET 1 0F 2 mm F INVENTORS VINCENT W. ANTONETTI GEORGE C. MALING JR. ALBERT L. PASCUZZO RUSSELL E WIZE ATTORNEY PATENTEBSEP 5 0m 3.688.867

SHEET 2 NF 2 H6. 4 CONVENTIONAL UNIT T FIBERGLASS UNITIZED g; 50 00:1

FREQUENCY IN CYCLES PER SECOND I FIG. 5

' CONVENTIONAL 0.0 1 UNIT STATIC PRESSURE (INCHES H 0) BACKGROUND OF THE INVENTION This invention relates to air blower packages, and more particularly, to a unitized acoustically improved blower package.

Computers have generally been cooled by forced air. As the cooling requirements have increased, the amounts of air and accordingly, the speed of the blowers have been increased. The blowers have been found at these higher speeds to generate noise which is above the maximum acceptable noise level. V

The air blowing or moving devices usually consist of a motor, centrifugal impellers, scrolls molded from rigid plastic or metal and a housing. In order to cut down the noise generated by the unit, mufflers have been attached to the outlets and sometimes to the inlets. These mufflers have sometimes been lined with a sound absorbing material which has had a coating on the inside surfaces to prevent the erosion of the fibers by the passing air.

It is an object of the present invention to provide an acoustically improved blower package which is unitized, that is, the motor, centrifugal impeller, scroll, mufflers and diffuser are formed in the same unit in which the noise radiation has been considerably reduced.

It is another object of the present invention to provide a unitized blower package in which the scroll, muffier and diffuser are molded within a single block of fibrous material.

It is a further object of the present invention to provide a unitized acoustically improved blower package in which the scroll, mufflers and diffuser are formed in a lightweight, good sound absorbing material block of sufficient density to maintain its form.

It is another object of the present invention to provide a unitized acoustically improved blower package of light weight design which is easily fabricated and provides a low loss of aerodynamic performance.

Briefly, the invention consists of a unitized acoustically improved blower package in which the housing is formed of a block of sound absorbing material of sufficient density to retain its form. A scroll-shaped chamber is formed in the housing block of material for containing the blower. A built-in muffler is formed within the housing and consists of a passage which extends from an outer surface of the housing to the scroll chamber. Likewise, a diffuser is formed in the block of material at the outlet of the scroll chamber and extends to an outer surface of the housing. The surfaces of the scroll-shaped chamber, the muffler, and diffuser are coated with a thin sound pervious material to protect the sound absorbing material from eroding and to present a low friction surface to the air passing thereover. A stiff outer shell surrounds the housing and has a good sound reflective characteristic. The shell has openings therein corresponding to the inlet openings of the muffler and the outlet opening of the diffuser.

The foregoing and other objects, features and advantages of the invention will be apparent from the fol lowing more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded schematic view of an improved unitized blower package for a pair of centrifugal blowers without the motor and blowers.

FIG. 2 shows a vertical side view and end view of the acoustically improved unitized blower package with the motor and centrifugal blowers mounted therein.

FIG. 3 shows a vertical section view of an acoustically improved unitized package in which an alternative method of providing cooling air to the motor is shown.

FIG. 4 is a graph of the noise level in decibels versus frequency in cycles per second showing in solid line form the performance of a prior art duplex blower assembly and in dotted form the present invention applied to a duplex blower unit.

FIG. 5 shows a graph of static pressure (inches H 0) versus CFM (0.075 lbs/FT density), the conventional unit being shown in black line and the acoustically improved unitized unit of the present invention being shown in dotted line form.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, there is shown an exploded view of an acoustically improved unitized duplex blower package. A block 10 is shown which is formed of a fibrous material such as fiberglass of sufficient density to be formable and to retain its shape. A four pound per cubic foot density of fiberglass has been utilized and has been found to be of good sound absorbing qualities as well as being easily formable and of relatively light weight. Air outlet openings 12 and 14 are formed within the fiberglass block 10 for passing the air from the centrifugal blowers (not shown) within the block. A motor chamber 16 for receiving the drive motor for the centrifugal blowers is shown. The particular arrangement shown in FIG. 1 is a block 10 for a double blower arrangement. That is, an impeller will be arranged on each side of the motor chamber 16. The fiberglass block 10 is split along a longitudinal line 17 down the middle so that the motor and centrifugal blowers can be located in chambers therein. The fibrous block of material 10 fits into a hard thin outer shell 18. The only requirement for the outer shell is that it provide a good reflective surface for sound attempting to pass therethrough. The shell 18 is preferably made of a hard thin plastic which helps to keep the weight of the entire unit low. Of course, inlet and outlet openings are provided in the shell contiguous with the inlet and outlet openings in the bottom of the block 10. A hard rigid mounting plate 20 fits over the top of the fibrous material block 10. The mounting plate 20 has openings 22 and 24 therein which are contiguous with the air outlet openings 12 and 14 in the top of the fibrous block, respectively. The mounting plate 20 has suspended therefrom the motor 23 and centrifugal blower wheels or impellers 25 and 26 which are shown in FIGS. 2 and 3. The mounting plate 20 is preferably made of a hard rigid plastic having good sound reflective properties. In actual use, the air inlets to the unit are covered with a filter 28 (FIG. 1). It is preferable that the filter 28 cover the entire bottom of the blower at the same time. However, it will be appreciated that separate filters can be provided which cover the inlet openings only.

FIG. 2 shows the shape of the scroll chambers 30,32 that are formed within the fiberglass block 10. The centrifugal impellers 25,26 are located within the scrollshaped chambers 30,32, respectively. The shape of the chambers 30,32 can best be seen from the end view of the block in FIG. 2. The scroll shape has been designed for the best air moving characteristics in conjunction with the centrifugal blower. The fiberglass block 10 is formed in two pieces since the block, as previously mentioned, is split along a longitudinal line 17. The surfaces of the scroll-shaped chambers 30,32 are coated with a rubbery synthetic material 34 such as neoprene. This coating provides sufficient protection for the fibrous surface such that the fiber is not eroded by the fast moving air generated by the blower. Also, the neoprene has a smooth finish and, therefore, provides a low friction surface to the moving air and thus does not affect the aerodynamic performance of the unit greatly.

The air inlets 36,38 are shown at the bottom of the fiberglass unit 10. Each inlet 36,38 is connected to its scroll chamber 30,32 by a passage 40,42 through the fiberglass block. The length of the passage 40,42 can be determined by the length of the fiberglass block 10 and the location of the scroll-shaped chambers 30,32 with respect to the ends of the block. These passageways 40,42 have their walls coated with the rubbery synthetic material 34 such as neoprene to prevent erosion similar to the coating which is applied to the scrollshaped chamber walls. These passageways are mufflers since they are formed within the fiberglass block and each have a predetermined diameter and length. FIG. 2 shows a double blower unit as was mentioned in connection with FIG. 1. The motor 23 is shown suspended from the top mounting plate 20. Of course, the-motor shaft 44 is utilized to support the impellers 25,26 within their respective chambers. Small diameter passages 46,48 are formed in the fiberglass block 10 between the motor chamber 16 and the scroll-shaped chambers 30,32. These small diameter passages 46,48 allow some of the air generated by the wheels 25,26 to be bled off into the motor chamber 16 for providing a circulating air cooling means for the motor 23. The air is exhausted from the motor chamber 16 through a further small diameter passage 50 which leads from the motor chamber 16 to the outer wall of the fiberglass block 10. The small diameter passages 46,48 from the scrollshaped chambers 30,32, the motor chamber itself and the motor cooling air exhaust passage 50, all have their inner walls coated with a rubbery synthetic material 34 such as neoprene to prevent erosion similar to the coating applied to the other inner surfaces of the fiberglass block. The diffusers 52,54 are that portion of the passages in the block 10 which lead from the scrollshaped chambers 30,32 to the openings 22,24 (FIG. 1) in the top plate 20. These diffusers 52,54 have predetermined shape which directs the air generated by the blower. Again, the surfaces of the diffusers 52,54 are coated with neoprene so as to provide a good noneroding surface for the fibrous surfaces and to provide a surface which does not affect the aerodynamic performance to any great extent. It will be appreciated that the diffuser can be of various lengths depending upon the location of the scroll-shaped chamber within the fiberglass block 10, Likewise, the fiberglass block could be shaped so that a long passage could be obtained from the scroll-shaped chamber to the surface of the block thereby serving as an outlet muffler.

FIG. 3 shows an alternative form of the blower unit wherein the motor cooling arrangement is changed. The arrangement has an air inlet passage 56 leading from the outer surface of the fiberglass block 10 to the motor chamber 16. The ends of the motor chamber 16 open directly into the scroll-shaped chambers 30,32 so that there is a complete air passage from the inlet 50 (FIG. 2) through the motor chamber to the scrollshaped chambers giving continuous circulation about the motor for cooling purposes. The main difference between the arrangement shown in FIG. 2 and the arrangement of FIG. 3, is that the previous arrangement exhausts the heat generated by the motor separately from the cooling air. In the present arrangement of FIG. 3, the heat generated by the motor is added to the air being blown by the centrifugal blower and therefore adds to the air which is to cool the units or devices to be affected.

Referring to FIG. 4, there is shown a graph of the sound intensity in decibels versus the sound frequency, in cycles per second. The solid line represents a plot of the sound power level versus the frequency of a conventional blower unit. That is, a blower unit in which the scroll-shaped chamber is formed of a metal or plastic and has associated therewith a conventional muffler diffuser, etc. It can be seen that this curve is for the most part above the 60 decibel level. A sound power level above 60 decibels especially in the 2,000 cycle per second frequency area is considered to be loud. The sound intensity in decibels versus the frequency in cycles per second of the unitized cooling unit of the present invention is plotted in dotted line form. It can be seen that at 2,000 cycles per second, there is approximately an 8 decibel improvement in the sound intensity. It should also be noted, that a considerable part of the dotted line curve falls below the 60 decibel line. The data was obtained from a standard duplex blower assembly and an acoustically improved unitized unit of the present invention, both operating from a 208 volt, 60 Hz power supply against a static pressure of 0.4 inches of water. A comparison of the aerodynamic curves for a conventional blower unit and the unitized blower unit of the present invention can be seen from FIG. 5. The solid line curve represents the conventional unit while the unitized unit is represented in dotted line form. The plot consists of the static pressure in inches of H 0 versus CFM (cubic feet per minute) (0.075 lbs/FT density). Again, identical motors, centrifugal blowers, mounting plates and outer housings were used. The difference between the units being compared was that the conventional unit utilized plastic scroll-shaped chamber while the new unit utilized fiberglass scroll-shaped chambers. As was expected, the aerodynamic performance of the fiberglass unit was lower than the conventional unit. However, this amounts to only 20 CFM out of 220 or approximately 10 percent at a typical operating pressure of 0.6 inches H O.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. An unitized acoustically improved blower package comprising:

a housing formed of a block of sound absorbing material of sufficient density to retain its form;

a scroll-shaped chamber formed in said block of said sound absorbing material for locating a blower;

a passage formed in said housing extending from an outer surface thereof to said scroll chamber, said passage forming a built-in muffler in said block of sound absorbing material;

a diffuser formed in said block of sound absorbing material leading from said scroll chamber to an outer surface of said housing for controlling the spread of the air from said blower;

a thin material coating applied to said scroll-shaped chamber surfaces, to said muffler passage surfaces and to said diffuser surfaces to protect said sound absorbing material from eroding and to present a low friction surface to air passing thereover; and

an outer shell surrounding said housing and having a good sound reflective characteristic, said shell having openings therein corresponding to said inlet opening of said muffler passage and said outlet opening of said diffuser.

2. An unitized acoustically improved blower package according to claim 1, wherein said housing block of sound absorbing material is fiberglass.

3. An unitized acoustically improved blower package according to claim 1, wherein said material coating applied to said scroll-shaped chamber surfaces, to said muffler passage surfaces and to said diffuser surfaces is a neoprene coating.

4. An improved blower package according to claim 1, wherein said block of sound absorbing material is slit longitudinally so that the blower can be located in the scroll-shaped chamber.

5. An improved blower package according to claim 1, wherein a motor chamber is located in said block of sound absorbing material adjacent said scroll-shaped chamber so that said motor can be utilized to drive said centrifugal blower.

6. An improved blower package according to claim 5, wherein a small diameter passage connects said motor chamber and said diffuser such that some of the cooling air passes through the passage from the diffuser to the motor chamber to provide circulating air for cooling of the motor and wherein a further passage extends from the motor chamber to the outside wall of the sound absorbing material block for exhausting the air from the motor chamber.

7. An improved blower package according to claim 5, wherein an air inlet passage extends from the outer surface of the sound absorbing material block to the motor chamber and the motor chamber has an opening between it and the scroll-shaped chamber such that ambient air passes through the inlet to pick up the heat from the motor and exhaust it through the scrollshzped chamber.

. An improved blower package according to claim 5, wherein a motor mounting plate is attached to the top of said block of sound absorbing material, said motor mounting plate having said motor suspended therefrom so that said motor and said centrifugal blower attached to said motor are suspended in their respective chambers, said motor mounting plate having an opening therein contiguous with the diffuser opening.

9. An improved blower package according to claim 5, wherein a scroll-shaped chamber is located on each side of said motor chamber in said block of sound absorbing material, each of said scroll-shaped chambers having a muffler passage and a diffuser associated therewith.

10. An improved blower package according to claim 9, wherein each of said chambers has a passage extending therefrom to said motor chamber for providing cooling air for said motor.

11. An improved blower package according to claim 9, wherein said motor chamber has an opening therefrom to each of said scroll-shaped chambers so that air entering said motor chamber from the outside through said inlet passage can exhaust into said scrollshaped chamber. 

1. An unitized acoustically improved blower package comprising: a housing formed of a block of sound absorbing material of sufficient density to retain its form; a scroll-shaped chamber formed in said block of said sound absorbing material for locating a blower; a passage formed in said housing extending from an outer surface thereof to said scroll chamber, said passage forming a built-in muffler in said block of sound absorbing material; a diffuser formed in said block of sound absorbing material leading from said scroll chamber to an outer surface of said housing for controlling the spread of the air from said blower; a thin material coating applied to said scroll-shaped chamber surfaces, to said mufFler passage surfaces and to said diffuser surfaces to protect said sound absorbing material from eroding and to present a low friction surface to air passing thereover; and an outer shell surrounding said housing and having a good sound reflective characteristic, said shell having openings therein corresponding to said inlet opening of said muffler passage and said outlet opening of said diffuser.
 2. An unitized acoustically improved blower package according to claim 1, wherein said housing block of sound absorbing material is fiberglass.
 3. An unitized acoustically improved blower package according to claim 1, wherein said material coating applied to said scroll-shaped chamber surfaces, to said muffler passage surfaces and to said diffuser surfaces is a neoprene coating.
 4. An improved blower package according to claim 1, wherein said block of sound absorbing material is slit longitudinally so that the blower can be located in the scroll-shaped chamber.
 5. An improved blower package according to claim 1, wherein a motor chamber is located in said block of sound absorbing material adjacent said scroll-shaped chamber so that said motor can be utilized to drive said centrifugal blower.
 6. An improved blower package according to claim 5, wherein a small diameter passage connects said motor chamber and said diffuser such that some of the cooling air passes through the passage from the diffuser to the motor chamber to provide circulating air for cooling of the motor and wherein a further passage extends from the motor chamber to the outside wall of the sound absorbing material block for exhausting the air from the motor chamber.
 7. An improved blower package according to claim 5, wherein an air inlet passage extends from the outer surface of the sound absorbing material block to the motor chamber and the motor chamber has an opening between it and the scroll-shaped chamber such that ambient air passes through the inlet to pick up the heat from the motor and exhaust it through the scroll-shaped chamber.
 8. An improved blower package according to claim 5, wherein a motor mounting plate is attached to the top of said block of sound absorbing material, said motor mounting plate having said motor suspended therefrom so that said motor and said centrifugal blower attached to said motor are suspended in their respective chambers, said motor mounting plate having an opening therein contiguous with the diffuser opening.
 9. An improved blower package according to claim 5, wherein a scroll-shaped chamber is located on each side of said motor chamber in said block of sound absorbing material, each of said scroll-shaped chambers having a muffler passage and a diffuser associated therewith.
 10. An improved blower package according to claim 9, wherein each of said chambers has a passage extending therefrom to said motor chamber for providing cooling air for said motor.
 11. An improved blower package according to claim 9, wherein said motor chamber has an opening therefrom to each of said scroll-shaped chambers so that air entering said motor chamber from the outside through said inlet passage can exhaust into said scroll-shaped chamber. 